Liquid ejector

Abstract

An ejector, which finds particular application as a fuel injector for a gas turbine engine, has an axially located passage ending as a nozzle having an internal surface facing radially inwardly towards the axis and which extends as an outboard cone about the axis of the passage and which terminates at a tip. The cone has a profile which replicates the unconstrained trajectory of the fuel leaving the passage. The outer surface of the ejector has a profile for accelerating a gaseous flow over the outer surface. Atomisation of fuel is improved along with relight capability, flame extinction and smoke production.

1 . A pressure jet liquid ejector comprising an axially located passage ending as a nozzle having an internal surface facing radially inwardly towards the axis, extending as an outboard cone about the axis of the passage and terminating at a tip, and an outer surface facing radially outwardly away from the axis and intersecting with the internal surface at the tip, wherein the outer surface has a profile for accelerating a gaseous flow over the outer surface. 
   
   
       2 . A liquid ejector according to  claim 1 , wherein the outer surface has a radius from the axis that varies along the axial length of the outer surface to provide the profile. 
   
   
       3 . A liquid ejector according to  claim 2 , wherein the radius along the axial direction decreases and then increases to provide an annular depression with an axially rearward lead in and an axially forward lead out. 
   
   
       4 . A liquid ejector according to  claim 3 , wherein the outer surface has an axially extending annular portion of constant radius between the end of the axially forward lead out and the tip. 
   
   
       5 . A liquid ejector according to  claim 1 , wherein the outboard cone extends outwardly at an angle between 30° and 70° to the axis. 
   
   
       6 . A liquid ejector according to  claim 5 , wherein the angle of the outboard cone replicates the unconstrained trajectory of swirling fuel leaving the passage in use at the highest fuel flow required. 
   
   
       7 . A liquid ejector according to  claim 1 , wherein the profile of the transition from the passage to the outboard cone matches the unconstrained fuel trajectory. 
   
   
       8 . A liquid ejector according to  claim 1 , wherein at least part of the passage is radially inward of an insulating sleeve for providing resistance to the transfer of heat from the gaseous flow to the passage, wherein the outer surface of the insulating sleeve provides at least part of the outer surface. 
   
   
       9 . A liquid ejector according to  claim 1 , wherein the passage has swirl means for imparting swirl to a liquid which flows through the supply passage in use. 
   
   
       10 . A liquid ejector according to  claim 1 , wherein the ejector has a housing which defines with the outer surface a gaseous flow passage through which, in use, a gas flows. 
   
   
       11 . A liquid ejector according to  claim 10 , wherein the gaseous flow passage has swirling means for imparting swirl to the gas flow. 
   
   
       12 . A liquid ejector according to  claim 1 , wherein the axis is the axis of a lean burn fuel injector for a gas turbine and the ejector further comprises a further fuel injector arranged concentrically about the axis and located radially outwardly of the outer surface.